Level control for a rail-mounted vehicle

ABSTRACT

The rail vehicle ( 1 ) comprises a sub-frame ( 2 ) and a wagon body ( 3 ) disposed above it. Between the wagon body ( 3 ) and the sub-frame ( 2 ) a spring stage ( 4 ) is provided and between the wagon body ( 3 ) and the sub-frame ( 2 ) at least one actuator ( 6 ) is provided which is arranged to bring the wagon body ( 3 ) from a raised travel position into a lowered load/unload position against a restoring force produced by the spring stage ( 4 ) to keep it in the load/unload position. The wagon body ( 3 ) is raised into a travel position by the restoring force upon deactivation of the actuator ( 6 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from provisional application No.60/376,057 filed Apr. 26, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a rail vehicle with a sub-frame and awagon body disposed above it, wherein at least between the wagon bodyand the sub-frame at least one spring stage is provided.

[0004] 2. Description of the Related Art

[0005] In rail vehicles of the above-mentioned type it can be the casethat when entering into a station the level of the floor in the wagonbody comes to lie higher than the floor level of the station. By reasonof the difference in level between the station and the upper surface ofthe floor of the wagon body a step may be formed in the transitionregion between the rail vehicle and the station.

[0006] Especially in rail vehicles which serve to transport people,these steps can constitute a considerable safety risk for passengers,for which reason a level adjustment may be carried out. To this end, thewagon body is normally lowered by reducing the dynamic spring travel inan active spring disposed between the wagon body and the sub-frame.However, the reduction in the dynamic spring travel of the active springhas the inherent risk that if the level adjustment arrangement fails,there will no longer be sufficient dynamic spring travel to ensure safetravel operation. In the event of a failure in conventional leveladjustment arrangements, travel operation is therefore no longerpossible. In order to avoid the problem just mentioned, some known leveladjustment arrangements for rail vehicles have a passive emergencyspring in addition to the active spring, which emergency spring shouldensure sufficient resilience in the wagon body if the active springfails.

[0007] A rail vehicle of this type is disclosed by, for example DE 19815 197 C1. The known rail vehicle has a support actuator which can bealtered in length in the vertical direction and is disposed between awagon body and a sub-frame. An emergency spring is disposedconcentrically to the support actuator in order to keep the supportdevice operating with sufficient travel comfort if the support actuatorfails or is overloaded.

[0008] A rail vehicle of the type mentioned in the introduction isdisclosed, for example in WO94/22702 A1. The known rail vehicle has ahydraulic spring leg which is disposed between the wagon body and thesub-frame. In order to lower the wagon body, the dynamic spring travelof the active spring leg can be reduced by draining oil in a springchamber. In the event of a loss of pressure, the vehicle can be loweredonto an emergency spring as is also known from DE 198 15 197 C1. Adisadvantage with this design is, as in all other known level adjustmentsystems which also use an emergency spring in addition to an activespring, that the spring travel of the active spring is limited“downwards” in the direction of the sub-frame by the emergency spring,for which reason it may be the case that it is not possible to lower thewagon body all the way to the floor level of a station, for example whenpeople are getting on and off.

BRIEF SUMMARY OF THE INVENTION

[0009] It is therefore an object of the invention to create a railvehicle with which it is possible to ensure both safe entry and exit ofpassengers in the region of a station and also level adjustment which isnot critically affected by a failure.

[0010] This object is achieved in accordance with the invention with arail vehicle of the type mentioned in the introduction in that betweenthe wagon body and the sub-frame at least one actuator is provided whichis arranged to bring the wagon body from a raised travel position into alowered load/unload position against a restoring force produced by thespring stage, and to keep it in the load/unload position, wherein thewagon body is raised into a travel position by the restoring force upondeactivation or failure of the actuator.

[0011] By means of the solution in accordance with the invention thevertical distance between the wagon body and the sub-frame can be variedwithin a large band width in a stationary rail vehicle. In theinvention, the spring stage disposed between the wagon body andsub-frame can be compressed by the actuator and the wagon body cantherefore be lowered to a desired level. The wagon body can be returnedto the travel position by a restoring force, which is produced by thespring stage, by release of the actuator.

[0012] The movement of the actuator into the load/unload position canadvantageously be limited by a stop.

[0013] Furthermore, the rail vehicle can be arranged to measure thevertical distance between the upper surface of a floor of the wagon bodyand a floor of the station, wherein a control device can be providedwhich is arranged to control the movement of the actuator into theload/unload position using the measured vertical distance.

[0014] The actuator can be hydraulic, electrical, mechanical orpneumatic in nature.

[0015] Furthermore, the spring stage can comprises [sic] at least onefail-safe passive spring, wherein this spring can be formed as a steelor rubber spring. The spring stage is advantageously a primary and/orsecondary spring stage of the rail vehicle.

[0016] Furthermore, when the actuator is hydraulic, the actuator canalso be formed as a vertical damper of the rail vehicle.

[0017] The invention with all further advantages is explained in moredetail hereinunder with the aid of a number of non-limiting exemplifiedembodiments which are illustrated in the attached drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0018]FIG. 1 illustrates a frontal view of a first embodiment of a railvehicle in accordance with the invention with a wagon body in a travelposition;

[0019]FIG. 2 illustrates a frontal view of the rail vehicle of FIG. 1with a wagon body in a load/unload position;

[0020]FIG. 3 illustrates a frontal view of a partial section of a secondembodiment of a rail vehicle in accordance with the invention with awagon body in a travel position;

[0021]FIG. 4 illustrates a frontal view of a partial section of a thirdembodiment of a rail vehicle in accordance with the invention;

[0022]FIG. 5 illustrates a frontal view of a partial section of a fourthembodiment of a rail vehicle in accordance with the invention;

[0023]FIG. 6 illustrates a frontal view of a partial section of a fifthembodiment of a rail vehicle in accordance with the invention;

[0024]FIG. 7 illustrates a frontal view of a partial section of a sixthembodiment of a rail vehicle in accordance with the invention;

[0025]FIG. 8 illustrates a frontal view of a partial section of aseventh embodiment of a rail vehicle in accordance with the invention;

[0026]FIG. 9 illustrates an exemplified embodiment of an actuator.

DETAILED DESCRIPTION OF THE INVENTION

[0027] In accordance with FIGS. 1 and 2 a rail vehicle 1 in accordancewith the invention has a sub-frame 2 and a wagon body 3. Between thewagon body 3 and the sub-frame 2 at least one spring stage 4 a, 4 b isdisposed. The spring stage 4 a, 4 b can be a primary 4 a and/orsecondary spring stage 4 b depending on the construction type of therail vehicle 1. Furthermore, the spring stage 4 b can be formed in amanner known per se as an active hydraulic spring, pneumatic springetc., wherein, however, at least one further passive spring 4′ isprovided.

[0028] During a halt in a station 5, one or a plurality of actuators 6,6′ can be used to draw the wagon body 3 towards the sub-frame 2 into aload/unload position, as shown in FIG. 2, against a restoring forcewhich is produced by the spring stage 4 b, in which load/unload positionthe level of a floor upper surface 7 of a floor extending in the wagonbody 3 lies approximately at the level of the footway of the station 5.The restoring force is then produced by the passive spring 4′.

[0029] The actuator 6, 6′ can be, for example hydraulic, electrical,mechanical or pneumatic in nature. The actuator 6 or actuators 6, 6′ canbe arranged on the rail vehicle 1 under consideration of the respectivestructural or constructional properties of the rail vehicle 1 so thatretrofitting of existing rail vehicles 1 is possible. In the case of ahydraulic actuator the actuator or actuators 6, 6′ can also be formed asvertical dampers on the rail vehicle 1.

[0030] When the suspension 4 b has an active spring this spring can bemade to act as a passive spring. For example, in the case of an activehydraulic spring the behaviour of a passive spring can be forced bynon-drainage of oil during its compression. If the spring stage 4 b ispurely passive the wagon body 3 is lowered in the station 5substantially only by the actuator 6, 6′.

[0031] However, it is also possible to lower the wagon body level in amanner which is known per se, for example by oil draining of an activespring, wherein the actuator 6, 6′ in this case only becomes active whenthe wagon body 3 sits on a passive emergency spring and the level of thefloor upper surface 7 still lies above the station level. In this casethe actuator 6, 6′ draws the wagon body 3 towards the sub-frame 2against the restoring force of the emergency spring. The passiveemergency spring is therefore compressed beyond its fixedly set “travelexpansion” which normally cannot be passed statically. Upon release ofthe actuator 6, 6′ the emergency spring can expand again and lift thewagon body 3 into a permissible travel position. The passive emergencyspring is preferably formed as a rubber and/or steel spring.

[0032] If the suspension 4 b behaves in an exclusively passive mannerduring lowering of the wagon body 3, the difference in the state of thesuspension 4 b between the load/unload position and the travel positionis merely that in the load/unload state the suspension 4 b is pretensioned with respect to the travel position by the actuator 6, 6′.Therefore in a position which is lowered with respect to a travelposition illustrated in FIG. 1 a restoring force acts upon the wagonbody 3 in the direction of the permissible travel position.

[0033] In the case of passive suspension 4 b the restoring force changesin dependence upon the deflection of the actuator 6, 6′. By means of theassociation between the restoring force and actuator deflection it isensured that, as already described above in the event of a failure inthe actuator 6, 6′, the wagon body 3 can be returned to the startingposition, ie. to the travel position. By means of the solution inaccordance with the invention safe travel operation is ensured even ifthe level adjustment arrangement fails.

[0034] Upon release of the actuator 6, 6′ the wagon body 3 is raised tothe travel position by the suspension 4 b. If the actuator 6, 6′ failswhen the wagon body 3 is in the lowered position, the wagon body 3 israised to the travel position. In contrast to the known level adjusters,the wagon body 3, in this embodiment of the invention, therefore doesnot fall “downwards” towards the sub-frame 2 in the event of a failurein the level adjustment arrangement or in the actuator 6, 6′, as alreadymentioned in the introduction, but moves “upwards” into the travelposition.

[0035] The actuator 6, 6′ is preferably in a “non-powered” state intravel so that substantially no forces produced by the actuator 6, 6′and directed towards the sub-frame 2 act upon the wagon body 3. However,in principle it is possible for low forces to be exerted on the wagonbody 3 by the actuator 6, 6′ during a journey ie. in travel.

[0036] In order to limit the movement of the actuator 6, 6′ into theload/unload position a fixed stop (not shown herein) can be provided forthe actuator 6, 6′. This embodiment of the invention is especiallyadvantageous when all stations 5 on a line travelled by the vehicle 1are at substantially the same level with respect to the level of thetrack.

[0037] On the other hand, if the level of the stations 5 varies, therail vehicle 1 can be arranged to determine the vertical distancebetween the floor upper surface 7 of the wagon body 3 and a floor of astation 5, wherein a control device, for example an appropriatemicrocomputer, can be provided which is arranged to control the movementof the actuator 6, 6′ into the load/unload position with the aid of themeasured vertical distance.

[0038] In accordance with FIG. 3 each passive spring 4, 4′ can beassigned to an actuator 6, 6′, wherein each actuator 6, 6′ can bedisposed besides the respective spring 6, 6′. In order to limit themovement of the wagon body 3 towards the sub frame, each spring 4, 4′can comprise a stop 4 f, 4 f′ made of rubber. Each of the springs 4, 4′can comprise two spring discs 4 e, 4 e′, between which a coil spring 4 cis disposed. Further a rubber-layer spring 4 d can be disposed betweenthe sub frame 2 and the spring disc 4 e′ near to the sub frame 2.

[0039] The actuator 6, 6′ can also be disposed inside the respectivespring 4, 4′ as shown in FIG. 4. Further the rubber-stops 4 f, 4 f′ canbe arranged outside the springs 4, 4′. In order to limit the movement ofthe wagon-body 3 towards the sub frame 2, the wagon body 3 can comprisemeans 3 a, 3 a′ interacting with the rubber stops 4 f, 4 f′.

[0040] According to FIG. 5, the rubber layer spring 4 d can also bedisposed between the coil spring 4 c and the lower spring 4 d disc 4 e′,so that the rubber layer spring 4 d can be expanded by the actuator 6,6′.

[0041] In accordance with FIG. 6 the rubber stop 4 f″, 4 f″′ and theactuator 6, 6′ can be disposed inside the spring 4, 4′.

[0042] In the embodiment of the invention shown in FIG. 7 therubber-stop 4 f, 4 f′ is build around the coil spring 4 c.

[0043] According to FIG. 8 the rail vehicle can comprise just oneactuator 6 to bring the wagon body 3 from a raised travel position intoa lowered load/unload position. In the embodiment shown the primaryspring stage 4 a and the secondary spring stage 4 b can be tensioned bythe actuator 6.

[0044] In accordance with FIG. 9 the actuator 6, 6′ can be formed as ahydraulic actuator 6, 6′. The small arrows show the direction ofdistribution of the force in the actuator 6, 6′ while the wagon body 3is being pulled down into the load/unload position. In contrast, thelarge arrow shows the direction of movement of the wagon body 3.

I claim: 1 Rail vehicle (1) with a sub-frame (2) and a wagon body (3)disposed above it, wherein at least between the wagon body (3) and thesub-frame (2) at least one spring stage (4) is provided, characterisedin that between the wagon body (3) and the sub-frame (2) at least oneactuator (6, 6′) is provided which is arranged to bring the wagon body(3) from a raised travel position into a lowered load/unload positionagainst a restoring force produced by the at least one spring stage (4a, 4 b), and to keep it in the load/unload position, wherein the wagonbody (3) is raised into a travel position by the restoring force upondeactivation or failure of the actuator (6, 6′). 2 Rail vehicle asclaimed in claim 1, characterised in that the movement of the actuator(6, 6′) into the load/unload position is limited by a stop. 3 Railvehicle as claimed in claim 1 characterised in that it is arranged todetermine the vertical distance between a floor upper surface (7) of thewagon body (3) and a floor of the station (5), wherein a control deviceis provided which is arranged to control the movement of the actuator(6, 6′) into the load/unload position using the measured verticaldistance. 4 Rail vehicle as claimed in claim 1, characterised in thatthe actuator (6, 6′) is an electrical and/or mechanical actuator. 5 Railvehicle as claimed in claim 1, characterised in that the actuator (6,6′) is a hydraulic and/or pneumatic actuator. 6 Rail vehicle as claimedin claim 1, characterised in that the spring stage (4 a, 4 b) has atleast one fail-safe passive spring. 7 Rail vehicle as claimed in claim6, characterised in that the at least one fail-safe passive spring isformed as a steel or rubber spring. 8 Rail vehicle as claimed in claim1, characterised in that the spring stage (4 a, 4 b) is a primary and/orsecondary spring stage of the rail vehicle (1). 9 Rail vehicle asclaimed in claim 1, characterised in that the actuator (6, 6′) is formedas a vertical damper of the rail vehicle.